Female board members and the bottom line

As of April 2012, 15% of Fortune 500 boards have one or more female members. Organizations with boards which are characterized by 30% gender diversity “outperform those with no women by a wide margin measured through multiple metrics” [Source: SmartBlog on Leadership].

This poses a chicken-or-the-egg conundrum: are organizations more efficacious because of their gender-diverse boards or are more efficacious organizations more likely to be more equitable in their recruitment of board members?